1. Field of the Invention
The present invention relates generally to programmable logic controllers and, more specifically, to a method of embedding tooling control data within a mechanical fixture design to enable programmable logic control verification simulation.
2. Description of the Related Art
It is known that programmable logic controller (PLC) code is written by controls engineers after assembly tooling designs are completed and a manufacturing process has been defined. The creation of the programmable logic controller code is mostly a manual programming task with any automation of the code generation limited to “cutting and pasting” previously written blocks of code that were applied to similar manufacturing tools. Once the programmable logic controller code is written, it is used by a tool builder to fabricate subsequent hard tools used in the manufacture and assembly of parts for motor vehicles. The programmable logic controller code is not validated (debugged) until the hard tools are built and tried. A significant portion of this tool tryout process is associated with the debugging of the programmable logic controller code at levels of detail from a tool-by-tool level, to a workcell level, and finally at a manufacturing line level.
It is also known that a manufacturing line is typically made of three to twenty linked workcells. Each workcell consists of a tool such as a fixture to position a product, for example sheet metal, and associated automation, for example robots, that process the product, for example by welding. The workcell typically consists of a fixture/tool surrounded by three or four robots. The product is then transferred to the next workcell in the manufacturing line for further processing, until it exits the manufacturing line.
It is further known that the workcells for a manufacturing line can be modeled before the manufacturing line is implemented. Current modeling technologies, such as Robcad from Tecnomatix and Igrip from Delmia, for the manufacturing process are limited in scope to a workcell level, due to how these type of technologies represent and manipulate three dimensional data and tool motions. This scope limitation is due to the manner in which tooling geometry is defined and the manner in which tool motions are described and displayed to a user. The geometry representation is typically defined using Non-Uniform Rational BSpline (NURB) type equations, which are very exact and precise, but require intensive microprocessor calculations. The tooling and robotic motions are also microprocessor intensive in that the articulations and movements are described through the use of complex kinematic equations and solvers. Presently, there is no modeling mechanism to verify that the planned interactions between linked workcells is indeed feasible until the manufacturing line is actually fabricated and assembled on a floor of a manufacturing plant.
Therefore, it is desirable to embed tooling control data within a mechanical fixture design to enable programmable logic control verification simulation prior to tool fabrication, assembly, and tryout. It is also desirable to reduce the amount of time it takes to conduct virtual programmable logic control verification simulations. It is further desirable to increase the accuracy of virtual programmable logic control verification simulations. Therefore, there is a need in the art to provide a method of embedding tooling control data within a mechanical fixture design to enable programmable logic control verification simulation.